D 8.3.2 update ... D 8.3.3-dev ???

Hello
I just upgrade, with Composer, our D 8.3.1 site.

 composer update --with-dependencies
Do not run Composer as root/super user! See https://getcomposer.org/root for details
> DrupalProject\composer\ScriptHandler::checkComposerVersion
Loading composer repositories with package information
Updating dependencies (including require-dev)
Package operations: 0 installs, 1 update, 0 removals

- Updating drupal/core (8.3.1 => 8.3.2): Downloading (100%)

Writing lock file
Generating autoload files
Downloading (100%)Downloading (100%)Downloading (100%)Downloading (100%)Downloading (100%Downloading (100%)DownloadinDownloading (100%)Downloading (100%)Downloading (100%)Downloading (100%)Downloading (100%Downloading (100%)DownloadinDownloading (100%)Downloading (100%)Downloading (100%)> DrupalProject\composer\ScriptHandler::createRequiredFiles
VTR01 ⚡ root@mail01  /home/mysite/public_html 
VTR01 ⚡ root@mail01  /home/mysite/public_html 

VTR01 ⚡ root@mail01  /home/mysite/public_html  cd web
VTR01 ⚡ root@mail01  /home/mysite/public_html/web  ../vendor/drush/drush/drush status

Drupal version : 8.3.3-dev

Site URI : http://default
Database driver : mysql
Database hostname : localhost
Database port : 3306
Database username : mysite
Database name : mysite
Database : Connected
Drupal bootstrap : Réussi
Drupal user :
Default theme : enterpriseplus
Administration theme : seven
PHP executable : /usr/bin/php
PHP configuration : /etc/php/7.1/cli/php.ini
PHP OS : Linux
Drush script : /home/mysite/public_html/vendor/drush/drush/drush.php
Drush version : 8.1.11
Drush temp directory : /tmp
Drush configuration :
Drush alias files :
Install profile : standard
Drupal root : /home/mysite/public_html/web
Drupal Settings File : sites/default/settings.php
Site path : sites/default
File directory path : sites/default/files
Temporary file directory path : sites/default/files/tmp
Sync config path : ../config/sync

--------------------------

WHY Composer say it upgrade 8.3.1 --> 8.3.2
but after, it's the 8.3.3-dev installed ???

I composer.json, I have :

{
    "name": "drupal-composer/drupal-project",
    "description": "Project template for Drupal 8 projects with composer",
    "type": "project",
    "license": "GPL-2.0+",
    "authors": [
        {
            "name": "",
            "role": ""
        }
    ],
    "repositories": [
        {
            "type": "composer",
            "url": "https://packages.drupal.org/8"
        }
    ],
    "require": {
        "composer/installers": "^1.2",
        "cweagans/composer-patches": "^1.6",
        "drupal-composer/drupal-scaffold": "^2.2",
        "drupal/add_to_head": "1.x-dev",
        "drupal/better_exposed_filters": "^3.0@alpha",
        "drupal/big_pipe_sessionless": "^1.0",
        "drupal/console": "~1.0",
        "drupal/core": "~8.0",

Thanks